Question

Which of the following aqueous solutions will exhibit the highest boiling point?

• A. 0.01M KNO₃
• B. 0.01M H₂SO₄
• C. 0.01M C₆H₁₂O₆
• D. 0.01M Urea

Hint:

For colligative properties like boiling point elevation, the more particles a solute dissociates into, the greater the effect on the boiling point.

Answer 1

The Correct Option is B

The boiling point elevation is directly proportional to the molality of the solution and the van 't Hoff factor \( i \), which accounts for the number of particles the solute dissociates into.
- KNO₃ dissociates into 2 ions (K\(^+\) and NO₃\(^-\)), so \( i = 2 \).
- H₂SO₄ dissociates into 3 ions (H\(^+\), HSO₄\(^-\), and SO₄²⁻), so \( i = 3 \).
- C₆H₁₂O₆ (glucose) does not dissociate, so \( i = 1 \).
- Urea also does not dissociate into ions, so \( i = 1 \).
Since the boiling point elevation is proportional to \( i \), the solution with the highest van 't Hoff factor will have the highest boiling point.
Therefore, H₂SO₄ (which dissociates into 3 ions) will exhibit the highest boiling point.

Thus, the correct answer is (2) 0.01M H₂SO₄.